Electric metal-heating process



No. 6l5,l36. Patented Ndv. 29, I898.

G. D. BURTDN. ELECTRIC METAL HEATING PROCESS.

(Applicatiou filed Aug. 24, 1898.) (No Modal.)

UNITED STATES PAT NT Fries.

GEORGE D. BURTON, OF BOSTON, MASSACHUSETTS.

ELECTRIC METAL-HEATING PROCESS.

SPECIFICATION forming part of Letters Patent No. 615,136, dated November 29, 1898.

Applicati n fi August 24:, 1893. Serial No. 483,917. (No specimens.)

To all whom it may concern:

Be it known that I, GEORGE D. BURTON, a citizen of the United States of America, residing at Boston, in the county of Suffolk, in the State of Massachusetts, have invented certain new and useful Improvements in Electric Metal-Heating Processes, of which the following is a specification.

This invention relates to the art of heating metal for forging or other metal-working operations by immersing the metal or that portion thereof to be heated in a suitable bath and passing therethrough an electric c-urrent of such a character as to cause the formation of an electric are at or below the surface of the solution and around the metal to be heated,whereby theheating thereof is quickly effected.

The object of the invention is to effect the heating of two pieces at one operation by the same current for welding and brazing purposes.

The drawing represents a perspective view of an apparatus used in carrying out this process.

A receptacle 10, composed in whole or in part of wood, earthenware, or other insulating material and constructed in the form of a tank or other suitable vessel, contains a bath 20, in which the metal to be heated is inserted and partially or wholly immersed. A plate 11, preferably of lead, is disposed in the bath and serves as an anode, being connected, by means of a conductor 12,with the positive pole of a direct-current generator or other suitable source of current. The receptacle 10 may be provided with a lining of lead, if desired, or made of metal and made to act as one pole of the current.

The bath 20 consists of any suitable electrolyte which,with the current used,will cause the formation of a Voltaic arc surrounding the metal to be heated on the insertion thereof. Either an acid or an alkaline solution will answer the purpose. I have used a solution of sal-soda of a specific gravity of 1.805 at 84 Fahrenheit; also, a solution of equal parts of sal-soda and cream of tartar of a specific gravity of 1.255 at 77 Fahrenheit; also, a solution of hydrate of potassium of aspecific gravity of 1.130 at 77 Fahrenheit; also, a solution other hand.

of pulverized caustic potassium of a specific gravity of 1.215 at 78 Fahrenheit, or a solution of caustic potassium of a specific gravity of 1.210 at 79 Fahrenheit. I deem these solutions preferable to an acid solution, as the latter is apt to affect the temper of the metal. The strength of the solution and the character and proportion of the ingredients may be Varied without departing from the scope of this invention.

In carrying out this process one of the bars, as 100, to be heated is grasped by a pair of tongs 30,provided with insulating handles and carried in one hand, one of said handles being connected by a conductor 31 with the negative pole of the electric source, and the other bar, as 200, to be heated is held in the The lower ends of these bars are submerged in the bath and placed in contact with each other, being held near the surface. As soon as the metal touches the bath the circuit is closed through the anode 11 and the bath 20. A hydrogen envelop is instantly formed'around the submerged portions of the metal, and a voltaic arc is established between the bars and the solution through said envelop. One bar passes the current to the other, and under the action of the arc the submerged portions of the bars are heated to the required temperature in a few seconds or minutes. When the pieces have attained the proper heat, which is observed by the workman, they may be united by permitting them to fuse together at their point of contact. It will be observed that in this heating and welding process of the two bars of metal together a liquid is employed which is decomposed by the heating electric current, so as to set free the hydrogen that surrounds the bars of metal during the heating process, and the hydrogen becomes incandescent owing to its resistance to the passage of the electric current through it, and thus keeps the bars not only from contact with the fluid, but from contact with any oxygen which would form upon their surfaces in ordinary welding processes and interfere with the welding of them together. It is not always necessary to carry the heating of the bars to the fusing-point before welding them together, as by pressing one upon the other they may be welded or united at a somewhat lower heat-as, for instance, with iron in the plastic stage, so called.

The absence of all oxidation prevents the danger of burning the metal to a large degree in the welding.

The voltage of the current employed may vary from forty-five volts upward and the amperage from forty amperes upward, according to the size of the pieces to be heated. The bars call for what current is required to heat them-that is to say, the apparatus being capable of supplying sul'licient current to heat the larger pieces required to be heated when such a piece or pieces are placed in circuit with the bath they will take a maximum current. \Vhen a smaller piece or pieces are placed in circuit, the quantity of the current passing through the line is reduced. The current is thus regulated by the size of the piece or pieces being heated, and a rheostat or other means of regulation is dispensed with. The metal bars to be heated are held as near the surface as practicable, being submerged sufficiently to cover the parts to be heated and to cause the formation of the 11ydrogen jacket and the voltaic arc.

Instead of using tongs any automatic or other device may be employed for holding the metal to be heated without departing from the scope of the invention.

The piece held in the hand of the workman, as shown in the drawing, enables him to readily manipulate the piece, and as he has connection with only one pole all danger from shock is avoided.

I claim as my invention 1. The art of heating metal bars which 0011- sists in subjecting the parts to be heated while in contact with each other to the action of an electric arc sprung between them and an electrolytic bath.

2. The art of heating metal bars which consists in immersing or partiallyimmersing the parts to be heated in a suit-able bath, and

passing a suitable electric current through said bath and bars, said bars being in contact and one receiving current from the other.

8. The art of uniting two pieces of metal, which consists in subjecting them to the action of an electric arc sprung between them and an electrolytic bath, and fusing the parts together while in the bath.

4. The art of uniting two pieces of metal, which consists first in subjecting them to the action of an electric current, in an electrolytic bath in which an envelop of evolved hydrogen surrounds them, and secondly bring them into pressure contact with each other when at the proper heat until they unite, substantially as described.

5. The art of heating two pieces of metal, which consists in immersing or partially immersing the parts to be heated while in contact with each other in a suitable electrolytic bath and passing a suitable electric current through said bath and pieces, both of said pieces being connected with the negative pole of the electric source, and an incandescent gas envelop being formed around the submerged portions thereof.

6. The art of heating metal by electricity and regulating the amount of current consumed, which consists in immersing or partially immersing the article to be heated as a negative electrode in an electrolytic solution, and passing a variable electric current from a source of excessive supply through said solution and thence through said article, the current enteringthe solution over alarge contact-surface and passing out over-a relatively-contracted area, and being adapted to cause the formation of an electric are between said solution and said article, and the article being heated determining the quantity of on rrent and serving as a regulator therefor.

GEO. D. BURTON.

Vit-nesses:

CHAS. F. ADAMS, ()CIAN P. ADAMS. 

